Natural or artificial radiative environments (with neutrons, protons, heavy ions, flash x-rays, gamma rays) can disturb the working of electronic components. These disturbances are due to interaction between matter and the particles of the radiative environment. One consequence is the creation of parasitic currents in the component. The magnitude of the parasitic currents produced will vary according to the interactions between matter and particles. This results in the presence of localized charge collection areas in the component.
Such stresses created by heavy ions and protons are typically encountered in space by satellites and launchers. At lower altitudes in which aircraft move, stresses especially from neutrons can be noted. Such stresses may be encountered at sea level too and may affect electronic components embedded in portable apparatuses or in automobiles.
To be able to predict the behavior of components with respect to heavy ions, neutrons and protons especially for space and aeronautical applications, it is necessary to know the surface area of the charge accumulation zones as well as their position and dimension in depth. This presupposes the ability to create 3D mapping.
Classically, to assess the particle sensitivity of an electronic component to the particles of the radiative environment, the component is subjected to a stream of particles and the disturbances are accounted for. Inasmuch as the entire component is irradiated, this type of test does not allow for tracing back to the location of the charge collection zones. Furthermore, these tests are relatively costly because there are relatively few installations in the world capable of producing streams of particles. Finally, even if the nature of the particles coming from the particle accelerators is the same as that of the radiative environment, their energy may be different. This may lead to major errors, especially because of their lesser penetration into the component.
Small-sized beams may be extracted from the output of the particle accelerator. These microbeams can therefore be used to map the zones of sensitivity of a component. This mapping is done in a plane and reveals the location of the charge collection zones only superficially. No information on the location of the sensitive zone in depth is obtained by this type of test.
Until now, laser has been used chiefly as a tool for pre-characterising the sensitivity of the components to radiation. Just as with the particles of the radiative environment, laser can generate parasitic currents within the components when its wavelength is appropriate.
Laser has a very valuable advantage for studying the effect of radiation. Since the spatial resolution of a laser can reach relatively small dimensions as compared with the elementary structures contained in electronic components, it is possible, as in the case of a microbeam, to map an electronic component and identify its charge collection zones. By varying the focusing point of the beam in depth, it possible to map sensitivity in the third dimension too, and this can easily be done on an industrial scale. However, this knowledge is not sufficient to know the overall behavior of the electronic component under radiation.